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Aquifer storage and recovery (ASR) can augment water supplies and hydrologic flows under varying climatic conditions. However, imposing drinking water regulations on ASR practices, including pre-treatment before injection into the aquifer, remains arguable. Microbial inactivation data- Escherichia coli , Pseudomonas aeruginosa , poliovirus type 1 and Cryptosporidium parvum -were used in a human health risk assessment to identify how the storage time of recharged water in the Floridan Aquifer enhances pathogen inactivation, thereby mitigating the human health risks associated with ingestion. We used a quantitative microbial risk assessment to evaluate the risks for a gastrointestinal infection (GI) and the associated disability-adjusted life years (DALYs) per person per year. The risk of developing a GI infection for drinking water no longer exceeded the suggested annual risk threshold (1 × 10 -4 ) by days 31, 1, 52 and 80 for each pathogen, respectively. DALYs per person per year no longer exceeded the World Health Organization threshold (1 × 10 -6 ) by days 27, <1, 43 and 72. In summary, storage time in the aquifer yields a significant reduction in health risk. The findings emphasize that considering microbial inactivation, caused by storage time and geochemical conditions within ASR storage zones, is critical for recharge water treatment processes.

Private wells are susceptible to contamination from flooding and are exempt from the federal requirements of the Safe Drinking Water Act. Consequently, well users must manage (e.g., disinfect) and maintain (e.g., regularly test) their own wells to ensure safe drinking water. However, well user practices and perceptions of well water quality in the years following a natural disaster are poorly characterized. An online follow-up survey was administered in October 2020 to private well users who had previously experienced Hurricane Harvey in 2017. The survey was successfully sent to 436 participants, and 69 surveys were returned (15.8% return rate). The survey results indicate that well users who had previously experienced wellhead submersion or a positive bacteria test were more likely to implement well stewardship practices (testing and disinfection) and to report the feeling that their well water was safe. While the majority of well users believed that their water was safe (77.6%), there was a significant decrease in well water being used for drinking, cooking, and for their pets after Hurricane Harvey. Generally, these well users tend to maintain their wells at higher rates than those reported in other communities, but there continues to be a critical need to provide outreach regarding well maintenance practices, especially before natural disaster events occur. [ABSTRACT FROM AUTHOR]

Microbial contamination of private well systems continues to be a prominent drinking water concern, especially for areas impacted by floodwaters. Hurricane Harvey deposited nearly 60 inches of rain, resulting in extensive flooding throughout Houston, Texas, and neighboring counties. A sampling campaign to test private wells for fecal indicator bacteria was initiated in the weeks following flooding. Escherichia coli concentrations measured in wells were utilized in a quantitative microbial risk assessment to estimate the risk of infection for both drinking water and indirect ingestion exposure scenarios. Derived reference pathogen doses indicated that norovirus (1.60 × 10−4 to 8.32 × 10−5) and Cryptosporidium (2.37–7.80 × 10−6) posed the greatest health risk via drinking, with median health risk estimates exceeding the U.S. Environmental Protection Agency's modified daily risk threshold of 1 × 10−6 for a gastrointestinal infection. Bathing (1.78 × 10−6), showering (4.32 × 10−7), and food/dish washing (1.79 × 10−6) were also identified to be exposure pathways of health concern. A post-flood microbial risk assessment of private wells in the Gulf Coast has not previously been conducted. Estimating these health risks can provide scientifically supported guidance regarding which well water practices are safest, especially when well water quality is unknown. Developing this guidance is critical as coastal communities experience increased vulnerability to flooding. [ABSTRACT FROM AUTHOR]